In vehicles, aircrafts, telecommunications and other systems, batteries are often used to supply dc power to electrical devices (also referred to as electrical loads). Often, a power conversion circuit with a switched-mode dc-dc converter is used to deliver controlled power from the battery to the electrical loads. In automotive electrical systems one or more batteries are connected to a charging system that may be active whenever the powertrain, i.e., engine, is running, Additionally, hybrid or other powertrain systems may regenerate power and charge batteries or other storage devices under specific vehicle conditions, e.g., braking. Independent of the power source, electrical power is typically distributed to all vehicle electronics either as a direct or switched battery power feed.
In many applications, it is desirable to automatically identify (i.e., classify) the type of electrical loads connected to the battery. If the electrical loads can be automatically classified, short circuit current limits can be determined. If a short circuit condition is detected, load shedding may be initiated by selective removal of one or more electrical loads to prevent the battery from being completely discharged.
In vehicles designed to tow trailers, a trailer tow connector and the electrical components installed in the vehicle to control trailer loads are typically used to deliver electrical power to the trailer and also to monitor and control various devices or loads installed in the trailer. The trailer tow connector generally includes one or more output ports or pins adapted to deliver electrical power to the trailer devices or loads. The devices may include running lights, brake lights, parking lights, electric brakes, auxiliary battery, backup lights, fog lights and turn signals. Selected output ports or pins in the trailer tow connector are usually connected to a device that serves a particular purpose. For example, there may be an output port for operating the brake lights on the trailer and another output port for operating the right-hand turn signal and yet another for operating the left-hand turn signal. The trailer devices each may have a different operational current and a maximum current limit depending on its electrical characteristic. Also, electrical devices in a large trailer may draw more current than those in a small trailer. Consequently, a trailer tow connector designed to protect electrical devices in a large trailer may not be suitable for a small trailer.
In existing production trailer systems, trailer tow control circuitry is distributed through several electronic modules or may be encapsulated in a single body or trailer specific module. In these applications short or over current protection is limited to fixed value fuses or circuit breakers that are installed in the vehicle at time of assembly. Also, in many cases, trailer circuit switching devices are fused relays controlled by a high current ignition switch. Furthermore, many vehicles tow several trailers of varying size and features. A family SUV or truck may tow a small jet ski trailer (3 trailer circuits), a landscape flatbed trailer (4 trailer circuits) or a RV trailer (5 trailer circuits). Additionally, when a trailer is not attached to the tow vehicle the owner may attach a hitch lighting device (1-3 trailer circuits) for cosmetic or vehicle personalization. All of these trailers and hitch lighting devices have different operational current loads. For smaller trailers, the installed fuse may not protect the wiring in the trailer since the design short circuit protection is typically for a worst case scenario, which is based on the largest possible towable trailer allowed for that vehicle. Consequently, the fused or other fixed circuit protection device used generally detects hard shorts (direct shorts to ground) and does not protect against soft shorts (low ohmic shorts to ground) or other high current related malfunctions in trailer equipment. Furthermore, today's trailer tow designs offer protection without detection or annunciation of a short circuit condition or other malfunction to the driver.
Existing trailer tow connectors typically lack the capability to intelligently detect and classify electrical loads. Consequently, existing trailer tow connectors lack the capability to intelligently determine short circuit current limits based on the attached electrical device. Also, existing trailer tow connectors lack the capability to intelligently initiate load shedding in response to a short circuit condition as well as providing a resettable short circuit protection design.